1. Field of the Invention
This invention relates to a member for recording information. More particularly, it provides a member in which a thin film disposed on a predetermined substrate is irradiated with an energy beam such as laser beam, to form recesses in the irradiated parts and which is suited to perform the recording of information.
2. Description of the Prior Art
Heretofore, there have been promoted the developments of recording members which can attain high signal-to-noise ratios (S/N ratios) even when picture information etc. at very high densities are recorded for use in optical video disks. For example, a thin film of bismuth (Bi) and thin films of some chalcogenides have been known as the thin films of the recording members to overlie disk substrates. They are disclosed in Japanese patent application publications Nos. 40479/1971 and 20136/1979, Japanese Patent Application Public-disclosures Nos. 42849/1975, 51738/1975, 154602/1977 and 31105/1978, etc. These films, however, have been unsuitable as the recording members because of the irregular shapes of pits, and have been problematic in point of lifetime. As As-Te-based thin film which has been recently developed exhibits a high recording sensitivity and affords a high signal-to-noise ratio in case of recording information by forming pits by irradiation with an energy beam such as laser beam. An example of this film is seen in Japanese patent application publication No. 15483/1979. Both As and Te, however, oxidize when let stand in the air for a long term. Therefore, the recording medium still involves an unstability in a long-term use and has not been yet earnestly put into practical use.
Further, there have been proposals for eliminating such problems, but they cannot be said to be satisfactory. An example of the proposals is to reduce the concentration of As in the recording thin film, and is disclosed in Japanese Patent Application Public-disclosure No. 31106/1978.